The Mayan day of doom is officially history, and yet the world lives on.

Some of the experts are not surprised.

“The human species is the most resilient you can imagine,” says Andrew Miall, a professor of earth sciences at the University of Toronto.

Maybe so, but we would be wise to be humble just the same.

We may have survived Dec. 21, 2012 – a date that was supposed to mark the end of the world, according to some interpretations of an ancient Mayan prophecy – but that doesn’t mean we’re home-free.

After all, this planet of ours can be a perilous neighbourhood. Already, our species has suffered some very close brushes with oblivion, and will certainly do so again.

What follows is a cautionary tale on an existential theme. It turns out we’re damned lucky to be here.

Forget the Mayans, if you wish – but remember Lake Toba, the geographical feature that almost did us in.

Now a tourist attraction on the Indonesian island of Sumatra, the body of water known as Lake Toba very nearly became the ash-laden graveyard of humankind.

It remains the world’s largest active caldera, which is geologist-peak for a truly massive volcano, one whose earthly floor has collapsed beneath it, often producing a lake.

Roughly 74,000 years ago, Toba erupted in spectacular fashion — said to be the most violent such event in the past two million years — and the result very nearly brought the advance of homo sapiens to a sudden, heart-rending halt.

After all, the eruption was colossal. For comparison, consider the 1980 explosion of Mount St. Helens in Washington state, which spit about three cubic kilometres of material into the sky, a performance deemed pretty impressive by contemporary vulcanologists.

But that was nothing compared to Toba, which is thought to have sent 2,800 cubic kilometres of pulverized earth, rocks and vegetation spiralling above the Earth and into the atmosphere.

All of present-day India, Pakistan and the Persian Gulf region were buried in ash to a depth of 1.5 metres, it is thought, and temperatures plummeted around the globe.

At the time, human beings were busily populating the Indian subcontinent. But the vast plumes of ash and smoke produced by the eruption of Toba caused a severe volcanic winter that may have lasted 10 years or more. Most humans who didn’t suffocate soon perished from cold or hunger.

By some estimates, only several thousand members of our species survived the eruption, including as few as 1,000 “breeding pairs.”

That long-ago bottleneck in human development may explain why people around the world nowadays are so similar to each other, with far less genetic variation than the experts would expect from the fossil record.

In other words, we are all descended from an extremely small pool of ancestors — the few hardy souls who survived the blast at Toba and its frigid aftermath.

Despite that nearly terminal setback, humans went on to become the dominant creatures on the globe. Now, in an irony of possibly existential proportions, our species is threatening to do to the whole planet what Lake Toba once nearly did to us.

In a word: obliteration.

“Humans as a collective are among the world’s largest geological agents,” says Miall. “We deforested Europe. We’re busily deforesting North America. The Amazon rainforest is disappearing fast.”

Some experts believe the planet is now poised at the brink of an evolutionary crisis — a massive die-off of plant and animal life caused almost entirely by human activity.

Maybe this is what the ancient Mayans were getting at when they supposedly foretold the end of the world. After all, environmental degradation was almost certainly a powerful factor in their own decline as a civilization.

Miall takes a somewhat more hopeful view.

“The Earth has gone through some very dramatic cycles in the last few million years,” he says. “The climate of the Earth has been warmer than now. There’s no doubt that human interference is making this process more tenuous, but life has survived these cycles. It will again.”

Not all the experts are so sanguine, and more than a few see disaster looming ahead unless our species changes its gas-guzzling, carbon-emitting, consumer-driven habits.

“There are ways that you can push the Earth’s climate, and it doesn’t simply bounce back when you stop pushing,” says Drew Shindell of the Goddard Institute for Space Studies in New York. He was speaking in an interview with the U.S. Public Broadcasting System. “Is there a chance that we’ll push things into a new state where they simply won’t return to where they were before? I think, yes, there is a pretty high probability of that happening.”

In other words, our species may well have survived the terrors of Lake Toba. We may also have eluded the heavily hyped horrors of Dec. 21, 2012. But that doesn’t mean the clock has stopped ticking, for ourselves or for our planet.